However, it was refused by the Home Office for being just over two weeks late, a mistake the British Medical Association (BMA) described as “an honest oversight”.

Speaking to the Press Association, Mr Ong said: “Financially it has been a drain because I have not been allowed to work whilst all of this is still ongoing. This is a situation where I hold my hands up and say I should have looked in to it a bit more and possibly got some immigration advice.

“However, I made my application and paid for it before in time, so I didn’t think it would have been a problem.

“Here I am ready to get on board with helping and contributing to this country and health service and it is such a shame that the Home Office don’t see it that way.”

Mr Ong, who lives in Manchester, appealed against the Home Office’s “hellbent” decision to deport him, which was upheld by an immigration judge.

However, just 10 days later he was informed that the Home Office would be taking his appeal to a higher court in the hope of overturning it.

Mr Ong’s visa expired on 15 August 2017 and the first available appointment to extend it was not until 2 September.

When he attended the appointment, his application was rejected on the basis that he was too late.

Commenting on the moment he was delivered the news, Mr Ong said: “I was flabbergasted – my mouth hung open for a while.

“It’s just beyond crazy. They have actually gone as far to say that it wouldn’t be detrimental for me to go back to Singapore because it’s not somewhere I would be persecuted nor is my life in imminent danger. I was so shocked.”

Dr Chaand Nagpaul, BMA council chair, said: “This situation, in which a doctor who has committed the last ten years of his life studying, training and serving in the NHS faces deportation over what appears to be an honest oversight, beggars belief at a time when the Government is prepared to spend millions recruiting GPs from abroad.

“The Government knows there is a serious shortage of GPs in England, with too few medical students opting for the specialism, while experienced doctors reduce their hours or retire early – something which is having a negative effect on patient care.

“The Home Office must therefore move away from this hostile culture and any approach to immigration rules for doctors needs to be flexible and – ultimately – practical. For them to seemingly take such a strict stand in this case is utterly incomprehensible.”

A spokeswoman for the Home Office said: “All visa applications are considered in line with immigration rules and on the evidence provided.

“Dr Ong’s case is currently under appeal and it would be inappropriate to comment further whilst legal proceedings are ongoing”.

Speaking about what makes him want to stay in the UK and work within the NHS, Dr Ong said: “It’s that sense of camaraderie that you find in the NHS. There is a real sense of dedication. The people who work within it do it not just for the salary, but the goodwill they have in them. That carries the system through – even at a time when it’s purely melting down around us.”